INTRODUCTIONColorectal cancer (CRC) screening programmes exclude from invitation the patients who have been diagnosed with a CRC, under the assumption that they receive an intensive care according to protocols of follow up. In order to test such assumption, we evaluated the compliance of CRC patients recorded by the Veneto Tumour Registry (VTR) with the protocol for follow up of AIOM (Associazione Italiana Oncologia Medica), which prescribes two clinical examinations per year for at least 5 years and one colonoscopy in the first year, to be repeated, if negative, after 3 years and again after 5 more years.

METHODSWe considered the patients with a CRC recorded by the VTR during 2006-2009. We set the beginning of the follow up according to the date of the surgical intervention, as reported in the Hospital Discharge Records (HDR); if no surgery was reported, the date of incidence was used. Information about follow up (clinical examination and/or colonoscopy) was collected from HDR and Outpatients Records, that were available up to December 31, 2014. Vital status was evaluated up to the end of 2014 too. We evaluated compliance with follow up according to year of incidence, gender, age, Country of birth (as a proxy of citizenship), setting of diagnosis (screening, non-screening), Local Health Unit of residence. We considered as compliant with follow up those patients who, during a given year of follow up, underwent a clinical examination and/or a colonoscopy.

RESULTSWe included in the study 4,416 patients, who were resident in 7 different Local Health Units (median follow up: 5 years). The proportion of compliers with follow up was 65.3% in the 2nd year of follow up and then decreased to 51.8% (6th year) and 38.7% (8th year) (test for trend: p<0.0001).Compliance was higher among patients diagnosed more recently: 2nd year 62.7% vs. 64.3%; 5th year 54.7% vs. 60.3% among patients diagnosed in 2006 and 2009, respectively. Compliance was higher among 50-59 year old patients (2nd year: 75.4% vs. 35.7% in 80+ year old patients; 8th year: 52.6% vs. 7.5%) and among males (2nd year 66.8% vs. 63.2% in females; 8th year: 40.5% vs. 36.4%).Among 50-69 year old patients, compliance was higher among screen detected cases (2nd year 81.4% vs. 72.6%; 8th year: 49.1% vs. 46.7%).Finally, compliance among subjects who were born abroad was higher at 2nd year (70.1% vs. 65.2% in Italians), but lower at 8th year (29.6% vs. 45.2%).Multivariate analysis confirmed the lower compliance among 80+ year old patients and a trend of increasing compliance in subjects diagnosed in the most recent years; we finally observed a significant association between compliance and the Local Health Unit of residence.

CONCLUSIONSCompliance with follow up protocols is highest in the first years after diagnosis and progressively declines. The lowest compliance rates were recorded among oldest patients. The local organisation of pathways for follow up services influences compliance. These results represent useful indicators for planning and evaluation of services; in detail, colorectal cancer screening programmes should assess the individual compliance of each patient diagnosed with CRC before excluding him/her from invitation to screening.